[ntp:questions] Re: NTP configuration problem

J S geekreader at gmail.com
Wed Feb 15 17:06:35 UTC 2006


Thanks for the reply-

This is on Planet-Lab OS (http://www.planet-lab.org) where NTP is already
configured, but  I need to run my own NTP client for an experiment. I have
the root access to my slice, but since port 123 is alreadyin use, I am
facing this problem.

I was wondering if I can configure my machine for  just NTP client and not
the server, this way I can bypass the bind() operation. I know openntpd
permits this but I think it does not change the rate of the clock( that's
what I have read)

Regards
JS



On 2/15/06, Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>
> J S wrote:
> > Hello
> > I am trying to configure NTP client on a machine but observing
> > unusual log.
> >
> >
> > my ntp.config files read this
> >
> > driftfile /etc/ntp/drift
> > restrict ntp1.cs.wisc.edu nomodify ntrap noquery
> > server ntp1.cs.wisc.edu minpoll 4 maxpoll 4
> >
> >
> > My drift file reads 0.000
> > whereas tcpdump is unable to capture any packets
> <snip>
>
> Lose the restrict statement!
>
> Also, you should not specify minpoll and maxpoll without very good
> reason!  The defaults were carefully selected and apply to, perhaps, 99%
> of all installations.  By specifying the values you did, you load the
> server unnecessarily and practically guarantee poor timekeeping
> performance on your client.
>
> The University of Wisconsin has very good reason to object to such usage
> of their server!  See http://www.cs.wisc.edu/~plonka/netgear-sntp/
> Netgear was very fortunate to avoid a lawsuit and many operators of NTP
> servers probably wish that U-Wisconsin had sued Netgear for every dime
> they had; the example would have done a lot to prevent current problems.
>
> If you MUST use restrict statements, specify the numeric IP address and
> an appropriate value for the net mask.  Using the domain name in a
> restrict statement is not supported.
>
> Finally, it' a generally a good idea to add "iburst" to the server
> statement.  This gets ntpd initialized in about twenty seconds vs. five
> minutes!
>
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